Evaluation of the biomechanical efficacy of limited intercarpal fusions for the treatment of scapho-lunate dissociation.
An experimental model that uses a static positioning frame, pressure-sensitive film, and a microcomputer-based videodigitizing system was used to measure the contact areas and pressures in a group of wrists in their "normal" state, after ligament sectioning, which resulted in stage III perilunate instability and then following different types of simulated carpal fusions. Compared with a normal wrist, there is an overall decrease in load in the lunate fossa and a significant increase in load in the scaphoid fossa in the wrist with stage III perilunate instability. Scaphoid-trapezium-trapezoid and scaphoid-capitate fusions transmitted almost all load through the scaphoid fossa. Scaphoid-lunate, scaphoid-lunate-capitate, and capitate-lunate fusions all distributed load more proportionately through both scaphoid and lunate fossae. The positioning of the carpal bones within a limited carpal fusion was also found to affect the load distribution in the wrist. The scaphoid-lunate, scaphoid-lunate-capitate, or capitate-lunate fusions, with attention to the relative carpal alignment within the limited fusion seem to offer more promise for treatment of perilunate instability biomechanically than the scaphoid-trapezium-trapezoid or scaphoid-capitate fusions.
Viegas
S F
SF
Division of Orthopaedic Surgery, University of Texas Medical Branch, Galveston 77551.
Patterson
R M
RM
Peterson
P D
PD
Pogue
D J
DJ
Jenkins
D K
DK
Sweo
T D
TD
Hokanson
J A
JA
D000328:Adult; D001174:Arthrodesis; D001696:Biomechanical Phenomena; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology / Q000601:surgery*; D012667:Lunate Bone / Q000503:physiopathology / Q000601:surgery*; D008875:Middle Aged; D014955:Wrist Joint / Q000503:physiopathology / Q000601:surgery*